Electric explosion impact powder compaction device and method

Abstract

The invention provides an electric explosion compaction device and method for powder compaction, and belongs to the technical field of powder metallurgy. Comprising a power-on assembly and a guide assembly, and the power-on assembly comprises a pulse circuit used for generating pulse current, a gasification metal piece and two electrodes; the guide assembly comprises a base, a top cover, a section die fixed to the base and a stamping sliding block longitudinally sliding between the top cover and the section die, the section die is provided with a forming cavity, the stamping sliding block is provided with a pressing head inserted into the forming cavity, the portion, below the pressing head, of the forming cavity is filled with powder to be compacted, and an explosion cavity is formed between the stamping sliding block and the top cover. The pulse circuit connects the gasified metal pieces in series through the two electrodes, the gasified metal pieces are located in the explosion cavity, and the stamping sliding block is driven to move downwards through electric explosion so as to compact powder. The device has the advantages of simple and reliable structure and the like.

Description

Technical Field

[0001] The present invention belongs to the field of powder metallurgy and relates to an electro-explosion shock powder compaction device and method. Background Art

[0002] Powder compaction processes, with advantages such as high efficiency, energy conservation, strong material adaptability, and high microstructural controllability, have gradually replaced traditional forging or casting processes in fields such as automotive (main bearing caps, gears), aerospace (superalloy turbine disks), and medical (implants), showing broad application prospects. Traditional powder compaction processes include mechanical pressing and high-speed pressing. The former has a mature process and is suitable for mass production, but has problems such as a large density gradient and high residual porosity in the pressed products. The latter uses the high-speed impact of a hydraulic hammer to achieve instantaneous compaction (impact speed 1 - 30 m / s), which can significantly improve density and uniformity, but relies on a complex mechanical structure, has high equipment maintenance costs, and is difficult to achieve nanoscale grain control. High-energy rate dynamic compaction technologies developed in the past decade or two, including explosive compaction and electromagnetic pulse compaction, have shown good controllability in terms of density, uniformity, and microstructure. For example, explosive compaction can achieve adiabatic compression of powders through shock waves generated by explosive explosions (pressure 1 - 100 GPa, action time 10 - 100 μs), and can be used for low-ductility metal and ceramic materials to obtain compacts with a relative density exceeding 95%, but it is difficult to precisely control explosion parameters (explosive detonation velocity, charging speed), and there are safety and environmental protection issues. Electromagnetic pulse compaction uses electromagnetic force to drive a punch to impact at high speed (speed > 30 m / s) to perform high-speed pressing on powders, which can achieve rapid densification of powder compacts, and the compaction process is environmentally friendly, but there are problems such as coil heating, insulation aging, and structural stability under mass production, which affect the quality stability of products. Summary of the Invention

[0003] The object of the present invention is to provide an electro-explosion shock powder compaction device for the field of powder metallurgy in view of the above problems existing in the prior art. The technical problem to be solved by the present invention is to achieve high-efficiency and high-quality compaction of powders and improve the performance of components.

[0004] The object of the present invention can be achieved by the following technical solutions: An electro-explosion compaction device for powder compaction, characterized in that it includes an energizing component and a guiding component. The energizing component includes a pulse circuit for generating a pulsed current, a vaporized metal part, and two electrodes. The guiding component includes a base, a top cover, a mold fixed on the base, and a stamping slider longitudinally sliding between the top cover and the mold. The mold has a forming cavity, and the stamping slider has a pressing head inserted into the forming cavity. The forming cavity under the pressing head is filled with powder to be compacted. There is an explosion cavity between the stamping slider and the top cover. The pulse circuit connects the vaporized metal part in series through two electrodes, and the vaporized metal part is located in the explosion cavity.

[0005] The pulse circuit includes a pulse power supply, a switch, a resistor, and a capacitor connected in series. Both ends of the metal wire are connected in series to the pulse circuit through two electrodes.

[0006] Optionally, the vaporized metal part is a metal wire or a metal foil.

[0007] Furthermore, the vaporized metal part is made of aluminum material.

[0008] Furthermore, the operating environment of the electro-explosion is a liquid environment.

[0009] Furthermore, the filling liquid can be water.

[0010] Furthermore, insulation treatment is performed between the electrodes and the top cover. The contact position between the electrodes and the top cover is filled with an insulating layer to prevent the electrodes from short-circuiting with it, reducing the energy utilization rate and shock wave intensity of the electro-explosion.

[0011] Both ends of the metal wire are connected to the pulse power supply. After the conductive path is connected, a short-circuit discharge is formed. The metal wire is instantly vaporized and a plasma shock wave is generated in the explosion cavity. Due to the incompressibility of water, the attenuation of the shock wave in water is slower. After the shock wave acts on the inner wall of the explosion cavity, it pushes the stamping slider downward and drives the pressing head to move downward at high speed. The powder in the forming cavity forms a dense green compact under the high-speed impact of the pressing head, completing the electro-explosion shock compaction process of the powder.

[0012] Preferably, the green compact can be post-heat treated to further improve the strength and density of the green compact.

[0013] Preferably, the powder can be preheated before the electro-explosion shock to increase the fluidity of the powder during the shock process, obtain a denser green compact with fewer defects such as cracks, and improve the service performance of the green compact.

[0014] An axial electro-explosion shock wave powder compaction method includes the following steps:

[0015] 1) Before installing the lifting top cover and the stamping slider, add an appropriate amount of powder to the forming cavity and spread it evenly.

[0016] 2) Fill the explosion chamber with a filling liquid, which can be water;

[0017] 3) Connect a metal wire between the two electrodes, and then install the stamping slider and the top cover in sequence, submerge the metal wire in the filling liquid of the explosion chamber, and ensure good sealing of the explosion chamber; then press down the top cover and the stamping slider to apply a pre-pressure to the powder to be stamped.

[0018] 4) Set the discharge voltage of the pulse circuit, turn on the discharge switch, the pulse power supply discharges, the metal wire or metal foil vaporizes under the action of an instantaneous large current and forms a plasma shock wave, the shock wave propagates in the filling liquid, and drives the indenter to move downward, and the powder forms a green compact under the action of the impact force.

[0019] 5) Take out the green compact, and if necessary, carry out post-heat treatment on it to further improve the mechanical strength of the green compact.

[0020] Preferably, after the metal wire is connected to the electrode, it can be integrated on the robotic arm to improve processing efficiency.

[0021] Preferably, no metal wire needs to be added between the two electrodes. Through the electrohydraulic effect, the electrode gap is broken down to form a plasma channel, the liquid is vaporized and expanded by Joule heating, and energy is instantaneously released to generate a shock wave to complete the impact compaction process of the powder.

[0022] Generally speaking, compared with the prior art, the technical solution proposed by the present invention has the following beneficial effects:

[0023] 1) High degree of automation. Electro-explosion uses electric energy as the energy source, and the detonation time and energy can be precisely controlled, which is convenient for automated production;

[0024] 2) High production efficiency. The entire process of electro-explosion is completed in milliseconds, and the installation process of aluminum wire and the like can also be assisted by robots, greatly improving the powder compaction efficiency;

[0025] 4) High safety factor. Compared with explosive compaction, electro-explosion impact compaction does not have the storage, transportation and operation links of explosives, and the storage, transportation and operation processes of metal wires are safer and more convenient;

[0026] 5) Low processing and maintenance costs. Compared with electromagnetic pulse compaction, electro-explosion impact compaction does not require coils, uses the electro-explosion of metal wires as the driving force, the equipment has good reliability, low failure rate, and lower maintenance and processing costs. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the electro-explosion axial impact powder compaction device according to the embodiment of the present invention;

[0028] Figure 2 It is a schematic diagram of another electro-explosion radial impact powder compaction device according to an embodiment of the present invention;

[0029] Figure 1 In it, 1. Pulse circuit; 2. Vaporized metal part; 3. Electrode; 4. Base; 5. Top cover; 6. Die; 7. Stamping slider; 8. Forming cavity; 9. Pressure head; 10. Explosion cavity. Specific embodiments

[0030] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0031] Figure 1 An electro-explosion impact powder compaction device provided by an embodiment of the present invention, the device mainly consists of a fixed base 4, a pulse circuit 1, a vaporized metal part 2, an electrode 3, an explosion cavity 10 and a forming cavity 8. The base 4 mainly provides a positioning basis and a fixing function for the entire device. The pulse circuit 1 is mainly used to provide the high-energy pulse current required for electro-explosion, and mainly consists of a switch K, a resistor R, and a pulse power supply. The pulse power supply therein can be composed of multiple capacitors C connected in parallel or in series to generate pulse currents with different pulse widths and peak values to adapt to different scenarios. The vaporized metal part 2 can be a metal wire or a metal foil, which is used to generate an electro-explosion shock wave. Its two ends are respectively connected to the positive and negative electrodes of the capacitor C through the electrode 3. An insulating layer is filled between the electrode 3 and the top cover 5 and the forming seat fixedly connected to the top cover to prevent current bypass and reduce the energy utilization rate and shock wave intensity. An explosion cavity 10 is formed between the forming seat and the stamping slider 7. A filling liquid is added to the explosion cavity 10. The filling liquid can be water. Compared with the air environment, the shock wave intensity decays more slowly in the liquid atmosphere, and a greater driving force can be generated to form a more dense green compact.

[0032] For further illustration, the metal wire used to generate the electro-explosion shock wave can be made of commonly used aluminum and its alloys, or copper and its alloys, or other metal and alloy materials.

[0033] After setting the discharge voltage of the pulse power supply, the discharge switch K is turned on, and the pulse current flows into the metal wire. Due to the rapid deposition of energy at the metal foil or metal foil, the metal wire or metal foil successively undergoes processes such as solid-state heating, melting and liquid-state heating, vaporization expansion and phase explosion, plasma formation and arc breakdown, and shock wave and energy release. The vaporization expansion and the rapid expansion of the plasma channel will generate shock waves in the surrounding liquid medium. The shock wave intensity follows the instantaneous line source energy release model. The peak pressure of the shock wave at the explosion center reaches the order of 1-10 GPa. After the explosion cavity 6 is affected by the shock wave, it moves axially downward, driving the pressure head 9 to move downward at high speed, completing the compaction and forming process of the powder body.

[0034] In the above solution, a pulsed capacitor with a pulse width range of 1 - 100 μs and a peak discharge voltage of 10 - 25 kV can generate a relatively large shock wave intensity to meet the requirements of powder shock compaction.

[0035] Multiple capacitors can be connected in parallel to increase the energy and intensity of the shock wave. The capacitance value of a single capacitor is 50 - 70 μF.

[0036] According to another aspect of the present invention, this embodiment provides an electro - explosion shock powder compaction method, including the following steps:

[0037] 1) Connect the exploding metal wire between the electrodes 3;

[0038] 2) Fill the groove in the explosion chamber 10 with liquid (water);

[0039] 3) Uniformly lay the powder to be compacted in the forming cavity 8, and then successively install the top cover 5; the mold 6; the stamping slider 7;

[0040] 4) Set the discharge voltage of the pulse power supply 1, turn on the discharge switch K, the pulse power supply C discharges, the metal wire vaporizes under the action of an instantaneous large current and forms a plasma shock wave. The shock wave propagates in the liquid environment and pushes the explosion chamber 6 downward. The pressure head 9 moves downward under the expansion action of the explosion chamber 10 to complete the shock compaction process of the powder body and form a green compact;

[0041] 5) Demold the green compact and take out the green compact.

[0042] Perform post - heat treatment on the green compact to reduce crack defects in the green compact and improve the mechanical strength of the green compact.

[0043] Adjust the length and diameter of the metal wire to control the process of energy deposition and the intensity of the shock wave. The diameter of the metal wire can be between 0.1 - 1 mm.

[0044] The beneficial effect of electric explosion impact powder compaction in this embodiment is that, compared with traditional hot isostatic pressing or mechanical compaction processes, the shock wave pressure generated by the electric explosion reaches a magnitude of 1-10GPa, which is much higher than the yield strength of the material. The powder material at this time has better fluidity, which effectively avoids the formation of pores and can form a denser compact. In addition, the repeated incidence and reflection of the shock wave between the powders makes the compact density close to the theoretical value and uniformly distributed. Compared with the problems of explosive detonation velocity control and charge density in explosive compaction, electric explosion can accurately control energy release by changing circuit parameters. The operation process is safe and simple, and no toxic or harmful pollutants are generated, meeting the requirements of green manufacturing. Electric explosion shock wave compaction technology achieves rapid densification of powder materials through efficient energy conversion and uniform pressure transmission. It has the advantages of high density, room temperature operation, environmental protection and safety. It is particularly suitable for the compaction of metal (Al, Cu, Ti, etc.), non-metal (carbon nanomaterials), alloy and composite powders. It has unique advantages especially for difficult-to-sinter materials (such as nanopowders and amorphous alloys), and can be used for powder pressing of machining tools, gears, bearings and other parts.

[0045] Figure 2 A schematic structural diagram of another device for electric explosion impact powder compaction provided in an embodiment of the present invention.

[0046] Figure 2 The electric explosion impact powder compacting device shown and Figure 1 The difference is that: the explosion chamber 10 does not need to be filled with liquid, the explosion process takes place in the air, and then the shock wave pushes the explosion chamber 10 to expand, and drives the stamping slider 7 to move downward, realizing the pressing process of the powder to be compacted and forming a compact; the vaporized metal part is a metal foil to achieve a larger range of electric explosion, so that the pressure-bearing surface in the explosion chamber is more evenly stressed.

[0047] The method is similar to that described above.

[0048] Relative to Figure 1 The electric explosion impact powder compaction process in a liquid environment is shown. Figure 2 The beneficial effects of the electric explosion impact powder compaction process in the air environment shown are: no need to add liquid, eliminating the need for medium storage, circulation filtration equipment and liquid filling / emptying processes, simplifying the equipment structure, no need to consider the sealing of the explosion chamber 10, avoiding the risk of liquid leakage, and making the processing process simpler, further shortening the process cycle and reducing equipment maintenance and energy consumption costs. The shock wave intensity is lower, which is suitable for the impact compaction process of small-sized parts, and expands the applicability of this technology in the field of precision micro-parts manufacturing.

[0049] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains may make various modifications or supplements to the described specific embodiments or use similar means for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. An electro-explosive compaction device for powder compaction, characterized in that, It includes an energizing component and a guiding component. The energizing component includes a pulse circuit (1) for generating pulsed current, a vaporized metal piece (2), and two electrodes (3); the guiding component includes a base (4), a top cover (5), a mold (6) fixed on the base (4), and a stamping slider (7) longitudinally sliding between the top cover (5) and the mold (6). There is a forming cavity (8) on the mold (6), and a punch head (9) inserted into the forming cavity (8) is provided on the stamping slider (7). The forming cavity (8) under the punch head (9) is filled with powder to be compacted. There is an explosion cavity (10) between the stamping slider (7) and the top cover (5). The pulse circuit (1) connects the vaporized metal piece (2) in series through the two electrodes (3), and the vaporized metal piece (2) is located in the explosion cavity (10).

2. The electro-explosion compaction device for powder compaction according to claim 1, characterized in that, The vaporized metal piece (2) is a metal wire or a metal foil.

3. The electro-explosion compaction device for powder compaction according to claim 2, characterized in that, The vaporized metal piece (2) is made of aluminum material.

4. The electro-explosive compaction device for powder compaction according to claim 2, characterized in that The operating environment of the electro-explosion is a liquid environment.

5. The electro-explosion compaction device for powder compaction according to claim 4, characterized in that, The filling liquid in the explosion cavity (10) is water.

6. The electro-explosion compaction device for powder compaction according to claim 2, characterized in that Insulation treatment is carried out between the electrodes (3) and the top cover (5).

7. A method for powder compaction using the electro-explosion compaction device according to any one of claims 1-6, characterized in that It includes the following steps: 1) Before installing the lifting top cover (5) and the stamping slider (7), add an appropriate amount of powder into the forming cavity (8) and spread it evenly. 2) Fill the explosion cavity (10) with the filling liquid, and the filling liquid can be water. 3) Connect a metal wire between the two electrodes (3), then install the stamping slider (7) and the top cover (5) in sequence, make the metal wire immerse in the filling liquid of the explosion cavity (10), and ensure that the explosion cavity (10) has good sealing performance; then press down the top cover (5) and the stamping slider (7) to apply a pre-pressure to the powder to be stamped. 4) Set the discharge voltage of the pulse circuit (1), turn on the discharge switch, and the pulse power supply discharges. The metal wire or metal foil vaporizes under the action of the instantaneous large current and forms a plasma shock wave. The shock wave propagates in the filling liquid and drives the punch head (9) to move downward, and the powder forms a green compact under the action of the impact force. 5) Take out the green compact, and if necessary, carry out post-heat treatment on it to further improve the mechanical strength of the green compact.

8. The electro-explosive powder compaction method according to claim 7, characterized in that, Carry out post-heat treatment on the green compact to further improve the strength and density of the green compact.

9. The electro-explosion powder compaction method according to claim 7, characterized in that, Preheat the powder before the electro-explosion impact to increase the fluidity of the powder during the impact process, obtain a more dense green compact with fewer defects such as cracks, and improve the service performance of the green compact.

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